when backdrop switches to [menu 3 v] //when "menu 3" is opened
go to front //so the menu item displays in the front
show //this opens up the menu

Recursion

This block can use recursion to continuously run scripts. An example is as follows:

when backdrop switches to [snow storm v] //a background switch must first be triggered to begin the recursion
. . .
switch backdrop to [sunny day v] //which will trigger the next script
when backdrop switches to [sunny day v]
. . .
switch backdrop to [snow storm v] //starts the cycle over

Workaround

When the backdrop changes, sprites with the When Backdrop Switches to () block, and the attribute as the backdrop being changed to (meaning the selected backdrop within the block is what is being switched to), the sprites will react and run their scripts beginning with this hat block. Broadcasts can be used to replicate this situation, though there may be a miniscule delay due to an extra block being added. The following is a workaround, often used in Scratch 1.x: